The invention relates to a method for reducing the storage requirement of a database and also an apparatus for carrying out the method.
Skilful modelling of a database is a problem particularly when very large volumes of data are involved. A concrete example is the desire or the necessity to store telephone tariff information or other individually assignable information units for any location-location combinations worldwide or at least for a relatively large country, for example Germany. The storage space available for this should be kept to a minimum. In Germany alone, however, there is already a total of 5604*5604 possible dialling code combinations. A total, therefore, of more than 30 million data records. In this case, each data record comprises at least two long-integer values of 4 bytes just for the dialling code, up to 25 bytes for the place name and at least 4 bytes for the assignment to the individual tariff zones. Each data record thus has at least 4+4+25+4=37 bytes. Consequently, the whole database would have a size of about 1.1 Gbytes, even without taking account of the so-called overhead, (indexing, etc.) of the respectively selected database. Skilful modelling of the database and classic compression technology would allow the storage requirement to be reduced to approximately 100 Mbytes. For certain database systems, which will be specified in more detail below, there is a desire to reduce the storage requirement further.
DE 34 25 844 A1 discloses a method for rapidly retrieving specific data records, produced by a telecommunications switching system or data processing system, in a data memory. The method proposes that when the data records are stored in the data memory, search terms are simultaneously stored as so-called key words in parallel therewith in a particular memory area. In the course of further processing or when the data records are printed out, whenever a key word corresponding to the search term is found, the counter position of an address counter for serial searching of the particular memory area is used to address the associated data record sought in a data memory.
Another search method for a data memory is disclosed in DE 39 08 684 A1. In this method, a finite management area, a search area located within the management area, and also search objects are predetermined in an n-dimensional co-ordinates system, the search objects which intersect the search area being determined.
These methods also permit only a slight reduction in the storage requirement.
The invention is therefore based on the object of specifying a method and an apparatus suitable for carrying out the method which enable the storage requirement to be reduced beyond the extent known to date in the case of certain databases.
The inventive method for reducing the storage requirement of a database is characterized in that information units to be stored are assigned to the points of intersection of an at least two-dimensional raster matrix, individual colour values are assigned to the information units located in the raster matrix and in that the image matrix thus formed is stored as database or as part of a database, preferably after the image matrix has been subjected to image compression.
The raster matrix is spanned by axes and information contents defined either by algorithms or by an assignent table can be assigned to the individual axis values. Suitable colour values used within the raster image matrix are, in particular, the known and defined RGB colour values, thereby enabling classic loss-free compression methods to be employed for a further considerable reduction in the storage requirement.
An inventive apparatus for carrying out the method according to the invention is characterized by the features of the claims of the present patent application with advantageous refinement possibilities in accordance with further dependent patent claims.